Current access control systems may electronically monitor and control access at an entryway to a secure area using, for example, a reader for reading an access card. Additionally, however, the secure area controlled by the access control system may include one or more entryways having a mechanical lock. For example, doors may have both mechanical security, e.g., a lock, and electronic access control, in this case, the mechanical lock mechanism takes precedence over the access control logic. Additionally, the doors having a lock may be opened by unlocking the lock using a typical door key, or alternatively a master key which overrides the access control system. Alternative access control systems and security systems may include electronically activated mechanical locks. Such control systems may also include multiple entryways, for example, on a floor of a building or the entire building, for example, as shown in commonly-owned, and co-pending U.S. patent application Ser. No. 11/782,557, the entire contents and disclosure of which is expressly incorporated by reference herein in its entirety. If a monitoring system has a door position switch, the system will have a record of the door opening, but not an identity and record of the key which opened the lock mechanically. Further, in an access control system which has a door position switch, the door opening event will appear as a forced entry. A shortcoming of such systems is that a person who is authorized to enter and uses the key entry, either a typical key or a master key, will trigger the forced entry alarm.
Additionally, an access control system may monitor the mechanical lock and identify and authenticate a key entry, as in the commonly owned application (U.S. Ser. No. 12/241,959) incorporated by reference above. However, a shortcoming of monitoring systems for mechanical locks occurs when a mechanical lock compromising technique is used to open the lock, such as lock-picking and lock-bumping. Current monitoring methods do not differentiate a valid key from lock compromising technique such as a bump key used in lock bumping, or a lock pick technique using a lock pick, and thus do not adequately detect lock compromising techniques. This situation is disadvantageous since the accuracy of the access control system is compromised due to an entry which is mistakenly identified as a valid key entry.
It would therefore be desirable to provide a method and access control system utilizing the method for identifying a lock tamper event when a lock compromising technique is attempted on a door lock. It would further be desirable for the method and access control system to initiate a tamper event signal to a monitoring station. It would also be desirable for the method and access control system to identify a lock tamper event when a lock compromising technique is attempted on a governing cylinder of a door lock.